The present invention is directed toward an apparatus and method for retaining circuit boards in a computer system. Specifically, some embodiments are directed toward retaining computer central processing units on a motherboard.
Three advantageous features of a computer system are: that the system be relatively easy to manufacture; that components of the system be easily accessible for maintenance purposes; and that the system be manufactured from standard components. Computer systems that provide improved manufacturability and maintainability have often been built with specially manufactured components that fit and operate together to give enhanced access to the interior of the system. However, relatively small numbers of several specially manufactured components are more expensive than standard components that are more widely available from multiple sources. A challenge of an improved computer system then is to provide an arrangement of standard components that is relatively easy to manufacture and maintain.
A typical computer system has a chassis that supports and encases a number of components of the computer system. The primary electrical interconnect component of a computer system is a backplane circuit board, such as a motherboard, that serves as a platform to which other components of the computer system may be connected. A motherboard primarily connects to one interior surface of the chassis in a plane parallel to the plane of the one interior surface. The motherboard typically has a number of sockets, slots, and plugs with which other circuit boards with components and other components with plugs may be connected to form electrical, and in some cases, mechanical connections between the circuit boards and components and the motherboard. Examples of circuit boards with components that may be plugged into the motherboard include one or more central processing units, main memory cards, video adapter cards, video acceleration cards, sound cards, SCSI controller cards, parallel or serial interface cards, game adapter cards, network cards, and others. Circuit boards with components such as these may connect with a motherboard through connectors along one edge of the circuit board. The edge connectors plug directly into a slot or socket in the motherboard. When attached in this manner, the circuit board may be substantially perpendicular to the motherboard. Examples of components with wires connected to plugs that may be plugged into the motherboard include hard disk drives, removable media disk drives, keyboards, pointing devices, printers, scanners, external modems, and others.
A computer system as described above can physically be viewed as a layered system. The base layer is the chassis. On top of the chassis is the motherboard layer. Above the motherboard is a layer of components, some of which mechanically and electrically connect to the motherboard through slots or sockets, and some that electrically connect through flexible wires with plugs. Some of the components may have an additional layer of component securing apparatuses for physically attaching components to the motherboard. Some systems may include cooling fans as an additional layer adjacent to components for cooling the components. While the prior art provides each of these layers, the prior art does not provide for the degree of use of standard components, for the ease of manufacturability, or for the ease of accessibility for maintenance that an improved device would provide.
A number of prior art systems provide enhanced access to underlying layers of a computer system through the use of hinged portions of the computer system. For example, the systems of U.S. Pat. Nos. 5,495,389, 5,701,231, 5,761,034, and 5,784,251 make system layers separable about hinges to provide access to components within the systems. The systems of U.S. Pat. Nos. 5,032,952, 5,172,305, and 5,777,848 provide enhanced access to some components by making power supplies of the computer systems partially removable about hinges. A primary failing of each of these seven systems is that they fail to allow use of standard motherboards, components, and chassis configurations. Some of the hinged power supply art does allow for use of some standard components such as standard power supplies. However, an improved system would not only provide an ability to easily remove the power supply layer, but other layers of the same system such as the component layer and the component securing layer.
One component that must be securely retained on the motherboard of a computer system is the central processing unit, or processor. A processor is often resident on a circuit board. The circuit board and processor together may be referred to below as a processor package. The Intel Corporation P6-based processor packages, for example, connect to the motherboard through what is known as Slot 1 or Slot 2 connectors. A Slot 1, or 242-contact slot connector, is used with PENTIUM II, PENTIUM III, or CELERON processor packages. The Slot 2, or 330-contact slot connector, is used with XEON processor packages. Slot 1 and Slot 2 electrical connectors are not, however, adequate to secure a processor package to a motherboard under normal service loads. Therefore, mechanical retaining structures must be added around a Slot 1 or Slot 2 connector to secure the processor package to the motherboard. A typical mechanical retaining structure is known as a xe2x80x9cgoal postxe2x80x9d because it physically resembles a football goal post with two vertical uprights. See FIG. 8 illustrating goal post xe2x80x9cGPxe2x80x9d and uprights xe2x80x9cURxe2x80x9d supporting a PENTIUM II or PENTIUM III processor package. Each of the vertical uprights is positioned to support a vertical edge of a processor package that may be supported in the connector. Support along the vertical edges, however, has not proven adequate to support the processor package. Similarly, a CELERON processor package is illustrated in FIG. 9.
To adequately support various Slot 1 and Slot 2 processor packages, a number of specialized retaining structures have been developed. For instance, U.S. Pat. Nos. 5,726,865 and 5,642,263 disclose such structures. A problem with these structures, as well as with the goal posts, is that they add expense to the computer system. Not only do the parts themselves add cost, but also installing the parts adds time to the manufacturing process.
The prior art processor package securing mechanisms have a number of other shortcomings. The mechanisms are designed to only secure a single processor package per mechanism. An improved mechanism could secure a single processor package or dual processor packages. An improved mechanism would also provide improved lateral support as well as vertical support to the processor packages. Lateral support would prevent side-to-side movement of the processor package and prevent the processor package from working loose under service loads. An improved mechanism would provide quicker release of a processor package or packages when desired by an operator. Easier access would allow for shorter manufacturing and maintenance times.
As discussed above, computer systems often include other components on circuit boards, in addition to processors, that connect to a motherboard through sockets or slots. One type of component on a circuit board is often referred to as an expansion board. Expansion boards include such circuit board types as peripheral component interconnect (PCI) boards, industry standard architecture (ISA) boards, and video adapter boards. Expansion boards allow additional circuits, and therefore additional functionality, to be added to computer systems. It is a standard practice to mount expansion boards substantially perpendicular to the motherboard.
Because expansion boards are not soldered into place on the motherboard, it is possible that the boards will become dislodged, lose electrical connectivity, and cease to function properly in shipping or under normal service loads. A number of designs have been proposed to adequately secure expansion boards to the motherboard. The standard configuration uses one screw per expansion board to secure one side of a mounting plate to the chassis of a computer. The mounting plate is secured to the expansion board. The other end of the mounting plate is inserted into a slot in the chassis. The expansion board is thus fastened relative to one wall of the computer chassis. This design assumes that the chassis is adequately stiff to prevent the motherboard, which is attached to one wall of the chassis, and the expansion board, which is attached to a second wall of the chassis, from moving relative to one another.
Expansion boards, however, often become dislodged from the motherboard even though fastened to one side of the computer chassis. Expansion boards are particularly susceptible to becoming dislodged when the board is located away from a wall of the chassis. When a board is located away from the wall of the chassis, that is, near the middle of the computer box, there is a lack of lateral stiffness in the wall of the chassis to which the motherboard is connected. Therefore, flexing of the chassis wall to which the motherboard is connected through a slot causes relative movement between the motherboard and the expansion board. Consequently, shaking of the computer or flexing of the chassis during shipping or handling can result in disconnection of expansion boards from the motherboard. Disconnection is also possible with computers used in non-stationary applications.
It can be a major inconvenience to a computer user when an expansion board is dislodged. For a user unfamiliar with the symptoms of the problem, it appears that the computer is materially defective. Even after the problem is identified, it is inconvenient and time consuming to partially disassemble the computer and re-seat the expansion boards. The superior alternative is to prevent the expansion boards from ever becoming dislodged from the motherboard.
The problem of expansion boards becoming unseated has been addressed by the prior art. For example, in U.S. Pat. No. 5,603,628 a pair of straps is used to hold a circuit board in a connector slot. A problem with the ""628 patent design is that the straps pass over and through the components of the board. Therefore, there is a possibility of damage to the board and the components of a board during installation or adjustment of the straps. Additionally, the ""628 patent requires that connection anchors be added to the connector slot. The anchors not only broaden the connector slot and consume motherboard area, but also require special manufacturing. The specific problem of expansion board retention in a personal computer was addressed in U.S. Pat. No. 5,715,146. However, the ""146 patent requires separate size adapter members to adequately secure expansion boards of differing heights. For each height of expansion board, a different size adapter must be added to the post member that supports the board. With different size adapters, production costs are increased and the possibility of manufacturing errors increases.
The prior art fails to provide an economical expansion board retention system that does not interfere with the components of the expansion board or consume motherboard area. Under the prior art, numerous adapters of varying sizes may be required to compensate for the fact that expansion boards are not uniform in height. Consequently, there is a need for an apparatus and method that adequately secures expansion boards to a motherboard without interfering with the components of the expansion board or the components of the motherboard. An improved device would also provide ease and speed of adjustment in retaining expansion boards.
As mentioned above, some components in a computer system require an additional cooling component such as a heat sink and/or a fan to properly dissipate the heat generated in portions of the computer system. An illustrative heat sink and fan combination of the prior art is disclosed in U.S. Pat. No. 5,309,983. The fan of the ""983 patent is, however, a miniature fan and therefore less capable of moving larger amounts of air as may be required to properly cool components of some computer systems. The miniature fan is also less common and therefore tends to be more expensive than a standard computer system cooling fan.
The need for heat dissipation capabilities is presently a concern and is becoming an even greater concern for future systems. In a Cahners EDN magazine article entitled xe2x80x9cKeeping HAL cool in 2003,xe2x80x9d Oct. 8, 1998, pp. 50-58, it was predicted through computer simulations based on projected power dissipations of computer components that, absent enhanced cooling solutions, hot spots of up to 493xc2x0 C. would occur in typical computer systems by the year 2003. Solutions to the problem where based on the addition of cooling fans and the management of air flow. The solution suggested by EDN is to put an active heat sink/fan similar to the one in the ""983 patent on the processor, and to put a fan on a wall of the chassis adjacent to the PCI card area. The solution applied to the processor is not very cost effective; however, since it requires the use of a more expensive active heat sink with a miniature fan. The problem with the suggested fan adjacent to the PCI card area is that either access to external plug portions of the PCI cards would be blocked by the fan placement or the fan would block drive bays in present day computer systems. Therefore, the EDN article identifies the problem thermal areas, but does not suggest practical solutions.
A better solution would provide for cooling air to pass over both the processor heat sink and the PCI cards without blocking access to either area when access is needed. Furthermore, an improved solution would employ standard cooling fans and cooling components to further reduce the cost of implementation. An improved solution would provide easy access to cooling components and would allow for maintenance on the components without the use of tools.
Another need that has not been met by the prior art is a standard system that provides for placement of various combinations of standard fans over critical areas. Computer systems have different cooling needs depending on the components included in the particular system. For example, a system with four high speed PCI cards and two high speed processors may need dedicated fans over both the PCI cards and the processors, and standard system exhaust fans. A system with only one expansion board and an older model or single processor may only need a standard exhaust fan to adequately cool all system components. An improved system would allow tuning of the airflow in the system by use of various combinations of fans.
One embodiment of the invention is a circuit board retaining apparatus for securing a circuit board relative to a connector in a chassis. The apparatus may include a circuit board cap coupled to the circuit board and a retaining structure coupled to the chassis and engaged with said circuit board cap to secure the circuit board when the retaining structure is in a first position. The retaining structure may be disengaged from the circuit board cap when the retaining structure is in a second position.
Another embodiment of the invention is a computer system that has a computer chassis and a first circuit board with a socket. The first circuit board may be coupled to the computer chassis. The system may also have a power supply coupled to the computer chassis. The power supply is electrically connected to the first circuit board. The system may also include a memory module and a second circuit board connected to the first circuit board through one or more sockets of the first circuit board. The system may have a circuit board cap coupled to the second circuit board, and a retaining structure coupled to the computer chassis and engaged with the circuit board cap. The retaining structure of some embodiments is to secure the second circuit board when the retaining structure is in a first position and to disengage from the circuit board cap when said retaining structure is in a second position.
Yet another embodiment of the invention is a circuit board cap for coupling to a circuit board and for engaging a retaining structure. Embodiments of the circuit board cap include a first extension from a first side of the circuit board cap for coupling to the circuit board to restrict movement of the circuit board relative to the circuit board cap. The circuit board cap may also include a shear mechanism extending from a second side of the circuit board cap for engaging the retaining structure. In some embodiments, the second side is on the opposite side of the circuit board cap from the first side.
Still another embodiment of the invention is a method of securing a second circuit board relative to a first circuit in a computer system chassis. An act of the method is to open a panel of the computer system chassis. The panel may also have a retaining structure. Acts of an embodiment of the method are to insert the second circuit board into a connector of the first circuit board, and to cap the second circuit board with a circuit board cap that includes a shear mechanism for engaging with the retaining structure. Another act of some embodiments of the method is to close the panel to cause the retaining structure of the panel to engage with the shear mechanism of the circuit board cap to substantially inhibit movement of the circuit board relative to the computer system chassis.